Small Cell Forum’s nFAPI will make virtualized HetNet a reality

London Tuesday 5 July 2016 – A multivendor, virtualized and future-proof HetNet – this is the vision that mobile operators have for their next generation deployments, and many want to move towards that ahead of 5G standards.

Small Cell Forum’s newly published Release 7 provides a critical enabler of that vision – a set of interfaces that will lay the foundations of an open, virtualized HetNet. All documents are available to access for free here>>

The Forum has extended one of its most successful specifications, the Functional API (FAPI) multi-vendor platform interface that has led to the accelerated deployments of small cells, to a virtualized small cell architecture, with the addition of nFAPI. nFAPI, a set of interfaces for supporting a virtualised MAC/PHY split will be pivatol in ensuring future interoperability for virtual small cell networks, enabling multivendor C-RAN economics today as well as a smooth evolution path to 5G. This unified framework which allows small cells from different vendors to work together seamlessly, enabling operators to deploy dense networks that will be interoperable and future-proof, and can combine physical and virtual elements.

The goal of interoperability has been central to the Forum’s work from its foundation, because an open multivendor platform encourages innovation and revolutionizes mobile network economics. As operators start to deploy dense, self-organizing HetNets – the overall theme of Release 7 – the interoperability vision is even more important to MNOs.

Back in 2014, the Forum’s Operator Group listed a set of issues which would be vital for them to adopt small cell virtualization. Prominent among them were that virtualization must “support innovation across a multivendor ecosystem” and that it must “deliver a phased roadmap aligned with longer term 5G directions”. And a major recent MNO survey found that 58% of operators plan to implement small cell virtualization by 2020, but 80% of those believe open APIs are essential to their plans.[1]

Mark Grayson (Cisco & SCF Virtualisation Champion) commented: “These priorities have guided the Forum’s work and ensured it has been closely aligned to the commercial requirements of MNOs. Operators are starting to implement centralization of small cell functionality together with virtualization and make plans for 5G, but as they make these significant commitments, they need to be sure that their deployments are open and future-proof.”

This is why nFAPI is so critical at this time. It aligns with the multi-vendor functional split which FAPI defines between the MAC and PHY layers, but allows the network functions to be virtualized. This provides a unified framework for operators to implement virtualized RAN, a trend which is becoming real in small cells more quickly than in the macro network.

Deployment of centralized architectures, especially in the enterprise, is already accepted as a way to simplify operations and enhance control of key functions like security, policy and resource co-ordination. nFAPI will accelerate that process by ensuring that no operator is locked into a single vendor’s offering. Operators will be able to deploy a combination of physical and virtualized elements, delivering efficiencies and new applications now; laying the foundations for emerging technologies like mobile edge computing (MEC); and with the flexibility to support 5G standards when they are defined.

Background information:

The document, ‘nFAPI and FAPI Specification’, is published as part of Small Cell Forum’s Release 7, a technical and commercial blueprint for deploying open HetNet and SON (self-optimizing network) and laying the foundations for 5G.

The FAPI (functional application platform interface) is an initiative within the small cell industry to encourage competition and innovation among suppliers of platform hardware, platform software and application software by providing a common API around which suppliers of each component can compete.

Many vendors therefore contributed to the document. The authors were Intel, IP.access and Cisco, and there was input additionally from L&T Infotech, mimoOn, Radisys, Texas Instruments, ASTRI and Qualcomm Technologies, Inc a subsidiary of Qualcomm Incorporated.

The architecture is generic to 3G or 4G small cells (and can adapt to 5G).

FAPI defines several APIs:

P1 – the security coprocessor interface

P2 – the service discovery interface

P3 – the GPS interface

P4 – the network listen results interface

P5 – the PHY mode control interface

P6 – the ciphering coprocessor interface

P7 – the main data path interface

M1 – the scheduler interface

Our specifications were extended to nFAPI (network functional application platform interface) following a virtualization study undertaken by Small Cell Forum, which examined different functional splits between virtual and physical network functions.

The MAC-PHY interface defined in FAPI was identified in the virtualization study as a suitable split point. This has motivated the Forum to define a transportable interface for the split small cell, to establish a scalable ecosystem with a converged approach to virtualization across multiple suppliers.